Biophysical properties of dry atopic and normal skin with special reference to effects of skin care products.
During recent years several highly developed non-invasive methods for evaluation of skin physiology and pathology have been introduced. Against this background, the present studies were undertaken with the primary aim of assessing the effects of various skin care products on some properties of the skin. Skin topography was measured by profilometry on skin replicas, friction with a newly developed friction instrument, capacitance with a Corneometer, and barrier function both with an Evaporimeter to assess transepidermal water loss (TEWL) and by application of an irritant followed by measurement of the resulting irritative reaction. Initially some of the techniques were used to further characterize the differences between dry atopic skin and normal skin. Dry skin exhibits increased values of roughness parameters and a reduced number of topographical peaks. TEWL is increased, indicating impaired barrier function. The friction and capacitance are lower and correlate significantly to each other, whereas TEWL does not appear to relate to either of these parameters. The use of a scrub cream removes the outermost part of the stratum corneum, resulting in a smoother skin. Application of moisturizers modifies the frictional response of the skin. The friction instrument gave results comparable to those of panelists trained in sensory evaluation. The study suggests that measurement of skin friction can be used to predict the degree of liking of moisturizers. Furthermore, moisturizers increase the skin hydration. They provide water directly to the skin from their water phase. Skin hydration also increases with increased degree of occlusion, as measured as a decrease in TEWL. Moisturizers may also alter the diffusional resistance of the stratum corneum and reduce the skin susceptibility to the surfactant sodium lauryl sulphate (SLS). Lipids in moisturizers may influence already developed SLS-induced irritation. A significantly lower degree of irritation was found in areas treated with canola oil and its sterol-enriched fraction than in an area treated with water. These findings emphasize that skin care products do not only form an inert, epicutaneous layer, but that they may penetrate and influence the structure and function of the skin.
Study implies that different people may have different degree of liking of moisturizers. Check!
SLS irritation is a common issue with the many skincare products. Study suggests skincare products may alter the diffusional resistance of your stratum corneum skin, reducing susceptibility to SLS. This I find it weird. Susceptibility will be reduced if the diffusional resistance is improved.
The only conclusion I can draw out is that, applying any input or external product to your skin alters and influence the structure and function of the skin, for the good or for the worse. Decide what you want for your TSW. My personal view is to always go natural. Our ancestors do not live in a world where skincare products are saturated and available in their lives. All they did was to keep their skin clean. They survived to have us today.